Claim: Sierra Nevada snowpack lowest in five centuries

Snowpack in California’s Sierra Nevada in 2015 was at the lowest level in the past 500 years, according to a new report led by University of Arizona researchers.

These two natural-color satellite images of the snow cover in the Sierra Nevada in California and Nevada show the last year with average winter snowfall, 2010, compared with 2015 — a year that had the lowest snowpack in 500 years. The images were taken by the Moderate Resolution Imaging Spectroradiometer on NASA’s Aqua satellite.CREDIT NASA/MODIS

The team’s research is the first to show how the 2015 snowpack compares with snowpack levels for the previous five centuries.

“Our study really points to the extreme character of the 2014-15 winter. This is not just unprecedented over 80 years — it’s unprecedented over 500 years,” said Valerie Trouet, an associate professor of dendrochronology at the UA Laboratory of Tree-Ring Research.

“We should be prepared for this type of snow drought to occur much more frequently because of rising temperatures,” Trouet said. “Anthropogenic warming is making the drought more severe.”

California’s current record-setting drought began in 2012, the researchers note in their report.

On April 1 of this year, California Gov. Jerry Brown declared the first-ever mandatory water restrictions throughout the state while standing on dry ground at 6,800-foot elevation in the Sierra Nevada. The historical average snowpack on that site is more than five feet, according to the California Department of Water Resources.

The lack of snow in 2015 stems from extremely low winter precipitation combined with record high temperatures in California in January, February and March, Trouet said. About 80 percent of California’s precipitation occurs in the winter months, she said. Snowpack level is generally measured on April 1 each year, a time when the snowpack is at its peak.

“Snow is a natural storage system,” she said. “In a summer-dry climate such as California, it’s important that you can store water and access it in the summer when there’s no precipitation.”

In past years the snows of the Sierra Nevada slowly melted during the warmer months of the year, and the meltwater replenished streams, lakes, groundwater and reservoirs. In a winter with less snow or with winter precipitation coming as rain rather than snow, there is less water to use during California’s dry summers.

First author Soumaya Belmecheri said of the extremely low snowpack in 2015, “This has implications not only for urban water use, but also for wildfires.”

Belmecheri is a postdoctoral research associate at the UA Laboratory of Tree-Ring Research.

To figure out snowpack levels for the past 500 years, Trouet and her colleagues used previously published tree-ring data that reflects annual winter precipitation in central California from 1405 to 2005 and annual snowpack measurements since the 1930s. The team also used a previously published reconstruction of winter temperatures in southern and central California that spanned the years 1500 to 1980.

Co-authors are Flurin Babst of the UA Laboratory of Tree-Ring Research, Eugene R. Wahl of the NOAA/National Centers for Environmental Information in Boulder, Colorado, and David W. Stahle of the University of Arkansas in Fayetteville.

The National Science Foundation, the U.S. Geological Survey and the Swiss National Science Foundation funded the research.

Trouet said, “There have been reconstructions of the drought conditions in California but no one’s looked at the snowpack in particular.”

After the extremely low snowpack levels in the Sierra Nevada were revealed in April, co-author Wahl wondered if it was possible to reconstruct the paleohistory of snowpack for those mountains.

Trouet thought the necessary data were available — so the team set to work.

Other researchers had already measured the width of tree rings for 1,505 blue oaks in California’s Central Valley from 33 different sites. Belmecheri and her colleagues put those measurements together as one long chronology, meaning the scientists had a blue oak tree-ring record that reached back reliably to the year 1405.

For those particular oaks (Quercus douglasii), the width of their annual rings reflects the winter precipitation they receive. Because the same storms that water the oaks also dump snow in the Sierra Nevada just to the west, the width of the blue oaks’ rings is a good proxy for snowpack in the Sierras, Trouet said.

Wahl had already published a reconstruction of central and southern California February-March temperatures from 1500 to 1980 that is independent of the blue oak tree-ring records.

Snowpack in the Sierras has been measured approximately since the 1930s, so the researchers checked their snowpack estimates from tree rings and the temperature reconstruction against actual snowpack measurements for 1930 to 1980.

The different measurements all lined up – when winter precipitation was lower and temperature was higher, snowpack was lower.

Peak snowpack is the measurement that hydrologists use to predict the amount of runoff that will occur in the summer, Trouet said.

The team’s next step, she said, is investigating and reconstructing the atmospheric circulation patterns that contribute to the California drought and the Sierra Nevada snowpack.

The different measurements all lined up – when winter precipitation was lower and temperature was higher, snowpack was lower.

Now why is my BS-meter bleeping at me?
This is one of those non-verifiable statements that climatologists are specialists in. The data “all lined up” did they ? What the hell does that mean in any mathematical or statistical language?
They kinda went up and down at similar times…. mostly, except when they didn’t.
Any mention of a correlation coefficient ? Nah, BS non-scientific claims passed off as a scientific study.

In past years the snows of the Sierra Nevada slowly melted during the warmer months of the year, and the meltwater replenished streams, lakes, groundwater and reservoirs. In a winter with less snow or with winter precipitation coming as rain rather than snow, there is less water to use during California’s dry summers.

My advanced apologies if my thinking is wrong here. Scenario:
400 years ago in the Sierra Nevada there is heavy snow. This is followed by a cold spring and cool summer reducing usual snow melt amounts. Wouldn’t it show up as a narrow tree ring indicating ‘less’ snow?
300 years ago in the Sierra Nevada there is average snow. This is followed by a very warm spring and summer increasing normal snow melt amounts. Wouldn’t it show up as a wide tree ring indicating ‘more’ snow?

Luke,
I can’t find where they indicate were the samples were taken from. In any case a warm spring and summer up in the mountains should release more water back then an show up in the tree rings. How would I necessarily know what the snowpack was like?
Assume average snowpack over the past 500 years (BEFORE 1930). Warm or cold springs would alter the amount of water released??
Even less information on the abstracthttp://dx.doi.org/10.1038/nclimate2809

If winter rainfall at lower elevations is correlated with tree ring width and snow pack at higher elevations (which they demonstrate with historical data) and higher temps at lower elevation are correlated with higher temps, and therefore greater snow melt, at higher elevations then they have the two pieces they need to support their conclusion.

Mike- here is the summary of the statistical information that you missed.
“We combined an extensive compilation of blue oak tree-ring series that reflects large-scale California winter precipitation anomalies7 (Supplementary Information and Supplementary Fig. 1) with a tree-ring-based California February–March temperature record8 in a reconstruction that explains 63% of the Sierra Nevada SWE variance over the instrumental period (Supplementary Table 1).”
63% is pretty impressive for long-term ecological data.

I don’t know if Anthony or the authors messed up but:
“Other researchers had already measured the width of tree rings for 1,505 blue oaks in California’s Central Valley from 33 different sites. Belmecheri and her colleagues put those measurements together as one long chronology, meaning the scientists had a blue oak tree-ring record that reached back reliably to the year 1405.
For those particular oaks (Quercus douglasii), the width of their annual rings reflects the winter precipitation they receive. Because the same storms that water the oaks also dump snow in the Sierra Nevada just to the west, the width of the blue oaks’ rings is a good proxy for snowpack in the Sierras,”
The Sierras are to the East of the Central Valley, not to the west, as is stated above.
Also, I am pretty certain that not all rain systems must necessarily pass over the tops of the Sierras, and could drop rain in the Central Valley without moving over them. Various weather systems could set up to drop rain in the Valley only

The USA Today edited the final quote to read “man-made global warming is making the drought more severe” to avoid obfuscation from “anthropogenic”. We mustn’t leave any room for doubt, or we might not get our UN bribe money.

Does anybody know just how much snow packs would be influenced by the amount of forest growth.
I presume that forests of conifers have a lot to do with whether snow gets blown away by lack of trees (specially conifers), and ends up melting at some lower elevation.
Conifers are like lobster traps; their steeply down turned branches, are designed to drop snow to the ground before it gets too heavy and breaks the branches off.
Once on the ground, the conifer canopy keeps the sun off the accumulated snow pack so it persists until the spring melt temperature rise.
So over the last 500 years, I dare say that Sierra forestry has thinned markedly due to lumbering, and land use conversion, so the efficiency of the conifer forests at capturing and preserving snow, is considerably diminished from what it was 500 years ago.
Just my opinion. I don’t think you can blame this on climate change. California is a desert. Get used to it, and try to capture the precipitation when you get it.
Another case of tree rings are the universal measuring instrument that accurately record, any physical parameter you want to know. (and all simultaneously; you just have to sort them out.)
g

What the hell are they doing counting tree rings on oaks in the central valley. The typical snow pack in the central valley, is about zero. Oaks don’t grow in snow pack.
And 500 years ago, in California, we had something that we no longer have; free flowing rivers.
So all that snow pack from 500 years ago, melted, and ran down into those many rivers we used to have, and never bothered to stop by any central valley oak trees on the way.
Yes a whole lot of Sierra melt runoff fed the central valley aquifers, but that water was long gone underground before any oak trees saw it.
Then of course we used to have Tulare lake; the largest (area) lake west of the Mississippi around Hanford Lemoore region. Well actually both of those places are in Tulare lake, instead of the water that used to be in it, before they drained it to get the farmland under it.
Oak tree rings don’t measure snow pack; they only care about local rains, and about a hundred other variables.
g

Right O George. Oaks live on mostly dry hilly and canyon lands where there is no runoff. They only survive on the moisture from rains and perhaps foggy weather, very rarely. You are correct. Snow in the Sierras have almost no watering effect on Oaks in general in the valleys and hilly areas of central California.

Yeah, it’s pretty dry this year, here in Sacramento. There’s not much snow visible on the mountains. (OK, today, we can’t even SEE the mountains because of the smoke from all the forest fires, but _LAST_ week…)
I’d even grant you that there might be less snow in the September mountains than in any September since 1845, but before that? I don’t think the Indians were doing snow depth surveys, and I’m skeptical of “proxy” measurements of something so transitory. And back 500 years?
Extraordinary claims require extraordinary proof. I’m not seeing it.

I don’t buy it. In the mid ’70s drought I was learning to ski at Squaw Valley. Half way down Mountain Run at about 7000 ft there were straw patches between the snow patches so rocks didn’t scar the skiis as you walked over.. at 6800 ft lodge level the only snow was old ice. Most everything was bare.
That was at peak season, not September.
So until there are A vs B photos of snow pack I suspect statistical humbuggery…

The population changed, but what does that have to do with snowpack as measured in the mountains? Sure, some people live in the foothills, but very few if any at the elevations where snowpack is measured.

Could be the effect of forest clearing decreasing precipitation locally & downwind (mtns). Didn’t studies of Kilimanjaro ice pack decrease implicate land clearing as the reason for snow pack decrease ?
Considering all the land converted to farmland in the central valley, seems like a good possibility.

California’s farmland wasn’t forested prior to cultivation.
Given most of the farms are irrigated, they are more likely to increase, not decrease available moisture.
There are studies that indicate average humidity in those areas has increased.

The Sierra has suffered extensive deforestation and denuding from high altitude gold mining, among other impacts affecting snow accumulation.
The current drought is no different from the many which have preceded it, except that it’s less severe and long-lasting.

Automatically blaming man for drought / worsening drought in California is simply guesswork. You can point out how bad drought is, but that is as far as you should go in my book. Megadroughts are a feature of the USA west of the Mississippi.
California has seen less than 7 years of drought. Now read on.

Paper
Extended drought in the Great Basin of western North America in the last two millennia reconstructed from pollen records
….Stine (1994) reviewed radiocarbon dates on submerged stumps in Mono Lake, Lake Tenaya, Osgood Swamp and the West Walker River and concluded that dry climate persisted in the eastern Sierra Nevada from ~1038 to 838 cal yr BP. The d 18O record from Pyramid Lake identifies a drought from 900 to 800 cal yr BP (Benson et al., 2002). Analysis of d18 O data in sediments from Walker Lake also identified the termination of a century long drought at 750 cal yr BP (Yuan et al., 2004)…http://www7.nau.edu/mpcer/direnet/publications/publications_m/files/Mensing_S_et_al_2008.pdf

IPCCIPCC Fourth Assessment Report: Climate Change 2007
Multiple proxies, including tree rings, sediments, historical documents and lake sediment records make it clear that the past 2 kyr included periods with more frequent, longer and/or geographically more extensive droughts in North America than during the 20th century (Stahle and Cleaveland, 1992; Stahle et al., 1998; Woodhouse and Overpeck, 1998; Forman et al., 2001; Cook et al., 2004b; Hodell et al., 2005; MacDonald and Case, 2005). Past droughts, including decadal-length ‘megadroughts’ (Woodhouse and Overpeck, 1998), are most likely due to extended periods of anomalous SST (Hoerling and Kumar, 2003; Schubert et al., 2004; MacDonald and Case, 2005; Seager et al., 2005), but remain difficult to simulate with coupled ocean-atmosphere models. Thus, the palaeoclimatic record suggests that multi-year, decadal and even centennial-scale drier periods are likely to remain a feature of future North American climate, particularly in the area west of the Mississippi River.

Didn’t the ice age end 10,000 years ago? Hasn’t it been generally warming since then? 500 years is 5% of the 10,000 year period, not unsubstantial and a big enough time bin to show snow or ice melting due to whatever ended the ice age. News flash…. Ice age is coming to an end.
Reasonable?

I recall the post glacial record showing early periods of warming higher than today with a gradual cooling – as interpreted from Greenland ice cores. Of course, lots of up and downs smoothed by the way gases are entrained into the ice layers.

Not only that but snowpack was lower in 1508. Christopher Columbus’ evil journey to the New World in 1492 caused the snowpack to be lower 500 years ago. We can blame him for the lack of snowpack in 1508 and 2015 since it is his fault for finding more land to expand the evil Western Culture.

“For those particular oaks (Quercus douglasii), the width of their annual rings reflects the winter precipitation they receive.”
Hold on a minute. Aren’t tree rings supposed to show temperature ala Briffa & Mann? Or is it just that one tree in Yamal that reflects temperature and all the others reflect precipitation? Or is it whatever they need it to be?

Well, given their subject matter (old trees), I’ll object to the “cherry picked” statement. They started at today and recreated the winter precipitation as far back as they could, which was 500 years. This is not cherry picking. It’s going to the limits of your data.
I seriously question whether they can claim so much from such a notoriously unreliable method. However, let’s object to what they did (overreaching, for example) instead of making up accusations that are just wrong

I’m always suspicious when they give a 50 year period of study ending 30 years ago. Why that period? what would show up if they did the next 30 years to the present? Or did they run into a problem with the data that might require Mike’s nature trick?

Ben,
CA is blessed with high-altitude trees thousands of years-old, so IMO stopping at 500 years is a cherry pick. They must know about the gigadrought during the Medieval Warm Period, for which there is ample evidence, including whole trees, not just their rings.
I agree with your statements about the reliability of their data, however.

“For those particular oaks (Quercus douglasii), the width of their annual rings reflects the winter precipitation they receive.”
Precipitation is only part of the equation. Timing of precipitation in the Sierras is another. Did the heavy rains come in fall or spring when the snowline was higher? Was it an El Nino year with relatively warm rains?
SR

500 years looks like a cherry-pick. Of course there’s less snow now, 500 years ago was smack in the middle of the Little Ice Age. Now if their finding had been for 5,000 or 10,000 years, that would be interesting. [and very likely wrong]

Bristlecone Pine rings can date to over 5,000 years. They are native to the Sierras and actually live in the show pack zone. I’m not exactly sure if they require as much surface water as is available since they get a lot of what they need from the air but pretty sure the growth rings would reflect the length of the growing season which would be from the time the soil over the roots was exposed to sunlight (more or less) to freeze up. A large snowpack would impact the start and an early snow the end of the season. I would think that snowpack conditions would be fairly uniform with multiyear oscillations.

California can be swamp, California can be desert. 500 year record drought will be followed by 500 year record rain! WOW! 200year record rains put 30 feet of water over the land at Sacramento in the early 1800s and filled the Tulary Basin nearly 50 feet. A 500 year flood would fill the valley and take over a year to drain! O..M…G………pg

Gov Brown was on TV last night blaming the fires on Climate Change caused by human emissions of CO2 (AKA Global Warming). He was very certain about this matter. It is not about El Nino, it is not about the drought, they are natural. It is about Climate Change caused by Mankind. It is amazing how confident he is when there hasn’t been any warming for 18 years.

There’s a funny story about a land grant at the southern end of San Francisco bay (where current San Jose resides) in which an enterprising immigrant discovered that he would be granted as much land as he could navigate in a boat so he loaded the boat up in a wagon and claimed territory all the way from Alviso to Hollister navigating from his boat hooked to a team of horses!

“Our study really points to the extreme character of the 2014-15 winter. This is not just unprecedented over 80 years — it’s unprecedented over 500 years,” said Valerie Trouet, an associate professor of dendrochronology at the UA Laboratory of Tree-Ring Research.”
Did you say ‘unprecedented’? Gee, never heard that before. The overuse of the word ‘unprecedented’ is unprecedented, but little else in this paper is. If I read that word one more time in one of these “studies”, I believe Pee-Wee will leap out of the screen belting, “YOU SAID THE SECRET WORD!!!”
“We should be prepared for this type of snow drought to occur much more frequently because of rising temperatures,” Trouet said. “Anthropogenic warming is making the drought more severe.”
And I was all worried they were going to make a wild leap of logic in order to keep the grant money flowing rather than simply say “the snowpack is the lowest we’ve seen based on available records”. After all, this is SCIENCE and it’s for the Earth and stuff!

Here we go again…observing that something is changing…using proxy data (due to the lack of actual data) to determine that it is “the worst on record”…and then making the jump without any real science to back it up that it is due to AGW.
Anyone else getting tired of this song and dance?

I was in graduate school at the time, and was wondering if they knew what were doing, and who they thought was going to get stuck holding the bag during the next dry spell. No one could imagine that the Gov. would be holding the bag for his previous incarnation as Gov.

Ahh yes, Vir. The universe does, after all, have a sense of humor. Unfortunately, not a very pleasant one.

Ambassador Molari to his aide, Vir Cotto.
Great site over at The Chiefio, I stop by nearly every day.

Reblogged this on Public Secrets and commented:
Visual proof this is a bad drought. Our water tables are recharged by the runoff from the mountains when the snow melts. No snow = no runoff = groundwater runs out.

Wait A Minute.
The tree ring data only goes forward to 1980, and they calibrate against the instrumental record from 1930. OK, fair enough.
Now:
They claim this year is outside anything in 500 years, so it has to be worse than anything since 1930. That means that this year is outside the calibration range. They had to extrapolate. Anybody want to bet on a linear extrapolation? And we know that growth rates flatten (on both ends) when the subject gets into extreme conditions. This leads to the very common sigmoidial growth curve, which is found *everywhere* in biology.
Doing a linear extrapolation on a sigmoidial curve, maybe? Getting extreme results, maybe?

This seems unclear. They used actual snowpack measurements to verify their tree ring data but only from 1930 to 1980. Since snowpack measurements don’t exist prior to 1930, fine. But, are there no snowpack measurements after 1980? After all, they used tree ring data to construct snowpack levels all the way from 1405 up to 2005. Couldn’t they verify past 1980 with existing snowpack measurements all the way up to 2005? And, are tree ring data unavailable after 2005 to further check against actual current measurements? Maybe I’m missing something? I do wonder if a Mannian splice is occurring. But, maybe that’s just me.

You are right, they only calibrated with snowpack data 1930-1980, when they have tree rings going all the way to 2005. I missed that one, first time through. So why not calibrate all the way through, 1930-2005? They would extend calibration from 50 years to 75 years. So why would they not do that? Then they use the 2015 snowpack data to interrogate the tree ring chronology to see if there are any similar situations. It seems, for this usage, the more recent calibration data, the better. Another dendro “Hide The Decline” moment?

@ Bill 2
Good point. It would be interesting to see if that is what they did.
Now suppose out of sample testing showed the validity of the calibration method. Would it then be permissible to make a new calibration over the entire range, and gain “goodness of fit” proportional to sqrt(n), even though out of sample verification is no longer possible? Or is that “bad science, no cookie for you” type statistics?

“Snow is a natural storage system,” she said. “In a summer-dry climate such as California, it’s important that you can store water and access it in the summer when there’s no precipitation.”
Dams are unnatural (usually) storage systems that solve completely the problem of moisture arriving as rain instead of snow. Some Americans may have heard of the Hoover Dam. It is important that you can store water and access it in summer when there is no precipitation. That’s why they built it.
Storing it as ‘snow’ promotes sublimation followed by evaporation from the streams whereas storing it in dams reduces the total loss because the streams flow down to the dams at a lower air temperature and higher humidity, less loss. Rain+dams increase the system efficiency. Snow + slow release doesn’t. Dams also allows for storage of vast quantities of water to get the community through long periodic droughts that occur from time to time to time. Like now.
The AGW comment was embarrassing for the poor guy. What GW? Where is the GW? In the Arctic? That GW? Does California’s rain come from the Arctic where it hardly ever snows or rains? What is the annual precipitation in the Arctic? The Arctic makes California look all wet.

Go to the Central Sierra Snow Lab website. Ask for data about precipitation at Donner Summit. In the four fiscal years ended 2015, the average annual precipitation was about 40 inches. From 1879 through 2015, the average was about 53 inches. In the four years ended 1919, the average annual precipitation was about 28 inches! There were 20 times since the 1879 (not independent four-year periods, many of the “times” had years in common) when the four year average annual precipitation was less than the average annual precipitation in the four years ended 2015. “Years” at the CS Snow Lab are years ended September 30th. Precipitation for the year ended 2015 is an estimate. Broadly speaking, the first half of the 20th century was a lot drier than the second half: from 1901 through 1950, average annual precipitation was 43 inches; from 1951 through 2000, average annual precipitation was 64 inches. While snow packs were low, the representative from the Snow Lab said that precipitation was a better measure of “wetness” than snow pack.

Not too sure of significance of report, simply documenting drought conditions in Sierra Nevada’s as related to blue oak annual growth (Oct-April). It has been previously documented that California had long term droughts in the past, including 10 plus year drought in 1770’s. No data from this investigation can show cause of drought, currently or in the past. The fact that there has been previous drought events of varying magnitude signifies a naturally occurring process, and 1770 was 180 years prior to significant anthropogenic CO2 atmospheric loading. Would like to read report and data, since this tree species also has significant vertical and lateral root system that utilizes groundwater and soil moisture for growth. To make a general correlation to snow/precipitation regime based on tree ring growth and claim future lack of snowpack because of AGW meme, is simply injecting a known falsehood (AGW) into a very basic study. Would be more valuable to propose other type of research that their study data could be used for in evaluating tree ring growth over last 500 years.

That 1770’s drought sounds like like a long Pacific La Nina that would have produced rain in Australia. Captain Cook in the 1770’s produced such a favourable report on discovering and reporting on the east coast of Australia that a Colony was founded by Arthur Phillp in 1788 in less favourable, possibly El Nino conditions. History is made.

According to the UC Berkeley Central Sierra Snow Laboratory, 1977 holds the record for lowest snowpack since 1879. 2014 was pretty bleak and in 2nd place with a snowpack at just 44% of normal. How do they get the “500 years” nonsense? 1881, 1885, 1924 were also low years. Is “500 years” a new synonym for “unprecedented”???

Well do I remember snowless 1977 in the Pacific Northwest. The switch in the PDO was plain to see then. The current drought in the northern Sierras, Cascades and Blue Mountains is probably just Nino-related weather, but could also mark another PDO transition.

Is this the same Trouet that Climate Audit recently showed he flipped one if the ocean proxy data sets upside down to show warming rather than cooling? Not sure how he still has a job after such nonsense.

Not sure I can distinguish clouds from snow over Nevada in the 2015 photo. What I see suggests that there may be an increase in a snowpack, say, around the White Mtns. Is there numerical data for this area?

I live in the northern central valley, and I watched them “chem-trail” all the storms (after December), and chase down any remaining potential rain cloud patches. I could watch the clouds disintegrate, like part went up sometimes, and part went down, till there was no part left with enough water to make rain.
I realize I’m not supposed to believe my own eyes, but I’m not into idiocy, so I go ahead and believe them. Been watching these sky’s since I was a kid, and it’s really rather obvious the “powers that be” have been messing with “my” atmosphere big time, for about ten years.
(Just thought I’d mention reality-land . . don’t let me interrupt your fantasies ; )

Good eye,the Whites indeed had plenty of snow. The few storms we got were passing south of the Sierra, putting the whites in the storm paths rather than in the shadow of the Sierra. Then w3 got more snow in apr-may than the whole rest of winter.

The Blue Oak study came from Griffin, D., and K. J. Anchukaitis (2014), How unusual is the 2012–2014
California drought?, Geophys. Res. Lett., 41, 9017–9023, doi:10.1002/2014GL062433
Regards wind speed and directions California’s precipitation more than elsewhere are driven by “atmopheric rivers”(ARs). Studies suggest globally that “at any given time, an average of more than 90% of the total poleward atmospheric water vapor transport through the middle latitudes is concentrated in four to five narrow regions that total less than 10% of the circumference of the Earth at that latitude.” from Eos 2011 Storms, Floods, and the Science of Atmospheric Rivers
California is especially sensitive to ARs (ie PIneapple Express) How much snow falls is determined by the path of those ARs and at what angle they hit the Sierra Nevada. Depending on ENSO’s affect on sea surface temperatures and how the resulting pressure systems guide the ARs snow fall will undergo extreme variations. That can be seen in studies of river flow and this Blue Oak study. As the Blue Oaks show the variations happen on ENSO and PDO timescales, and the current lack of precipitation is definitely extreme but not unusual. When California was getting floods there were papers arguing global warming will increase ARs hitting California Dettinger 2011). I have not yet read this new paper but I suspect now that we have a drought, opportunistic climate researchers will suggest AGW is causing the lack of snow. Some act researchers act like clueless day traders seeking headlines. When ENSO change the strength of the trade winds the headlines were global warming increased or decreased trade winds, depending on which way the winds blow

Abstract – 1998Relationships between winter atmospheric circulation patterns and extreme tree growth anomalies in the Sierra Nevada
Tree-ring data from mid-elevation (2000 m) giant sequoia (Sequoiadendron giganteum) and high elevation (3500 m) pines (Pinus balfouriana, Pinus albicaulis) were used to select extreme growth years from which temperature, precipitation and large-scale winter (November-March, NM) 500 mb circulation patterns associated with the extreme tree growth anomalies were examined.Winters preceding extreme high growth in both giant sequoia and pines are warm and wet and are characterized by anomalous low pressure in the northeastern Pacific Ocean and a tendency for southwesterly flow and advection of warm maritime air into California. For the pines, such winters exhibit a pattern of anomalous low pressure in the northern Pacific, anomalous high pressure over northwestern Canada and anomalous low pressure across the southern US. NM 500 mb heights suggest more meridional circulation during the warm and dry winters preceding extreme low growth in giant sequoia. Atmospheric circulation during these winters exhibits a persistent trough/ridge pattern between the central Pacific and the western US. Storms are deflected away from California during these winters. NM atmospheric circulation patterns associated with extreme low growth in the pines exhibit maximum westerlies north of their mean position and the tendency for enhanced ridging in the northeast Pacific, which advects cool dry air into the Sierra Nevada. As dendroclimatic reconstructions are more frequently employed in order to better understand past variability of temperature and precipitation, synoptic dendroclimatological studies such as this one provide useful insights about atmospheric circulation.http://adsabs.harvard.edu/abs/1998IJCli..18..725G

“Our study really points to the extreme character of the 2014-15 winter. This is not just unprecedented over 80 years — it’s unprecedented over 500 years,” said Valerie Trouet, an associate professor of dendrochronology at the UA Laboratory of Tree-Ring Research.
Ms. Trouet’s claim for decadal or centennial drought being “unprecedented” is overshadowed by the ranking of precipitation years by NOAA (Co-author Wahl’s employer). Their 120-year precipitation graph shows a continental U.S. with western regions with “much below average” precipitation, but certainly not “record driest”, in fact far from it. The years 2014-15 ranked as only California’s 28th driest.
It bears repeating (as Jim Steele has noted) that wind currents carry Pacific moisture hither and yon in any given El Nino, and in the last year or two many states in the center of the continent received record levels of precipitation. Out of 120 years on the NOAA record, 2014-15 were Wyoming’s 113th driest (only 7 years wetter), Colorado’s 112th driest, Texas’ 114th driest. In all, 20 states had “much-above-average” precipitation, and Oklahoma experience its wettest year on record.
The clustering of states with high precipitation is significant, in my opinion. Whatever the mechanism that deprived California and the Northwest of precipitation, the western and central plains got it in spades.
Drs. Wahl and Trouet would no doubt like to try to re-write some of that history. They’ll have to unless they can reconcile their own data with it. It was not California’s driest year by a long shot.
Current Colorado Reservoir levels:ftp://ftp.wcc.nrcs.usda.gov/states/co/resv/state/monthly/resmap.pdf
NOAA Statewide Precipitation Ranks, 120-year periodhttp://www.ncdc.noaa.gov/sotc/service/national/statewidepcpnrank/201409-201508.gif

Trouet said. “Anthropogenic warming is making the drought more severe.”
Per AR5, Technical Summary, TS.4.7:“Although the AR4 concluded that it is more likely than not that anthropogenic influence has contributed to an increased risk of drought in the second half of the 20th century, an updated assessment of the observational evidence indicates that the AR4 conclusions regarding global increasing trends in hydrological droughts since the 1970s are no longer supported. Owing to the low confidence in observed large-scale trends in dryness combined with difficulties in distinguishing decadal-scale variability in drought from long-term climate change, there is now low confidence in the attribution of changes in drought over global land since the mid-20th century to human influence.“

Letter To Nature – 11 September 2012
Justin Sheffield et al
Little change in global drought over the past 60 years
…….Previous assessments of historic changes in drought over the late twentieth and early twenty-first centuries indicate that this may already be happening globally. In particular, calculations of the Palmer Drought Severity Index (PDSI) show a decrease in moisture globally since the 1970s with a commensurate increase in the area in drought that is attributed, in part, to global warming4, 5……..Here we show that the previously reported increase in global drought is overestimated because the PDSI uses a simplified model of potential evaporation7 that responds only to changes in temperature and thus responds incorrectly to global warming in recent decades. More realistic calculations, based on the underlying physical principles8 that take into account changes in available energy, humidity and wind speed, suggest that there has been little change in drought over the past 60 years. The results have implications for how we interpret the impact of global warming on the hydrological cycle and its extremes, and may help to explain why palaeoclimate drought reconstructions based on tree-ring data diverge from the PDSI-based drought record in recent years9, 10.http://www.nature.com/nature/journal/v491/n7424/full/nature11575.html

As the mountains supply california with water I wonder what the snow pack was like back in 1948-
Californian Drought
Kills Bird Life
SAN FRANCISCO, March 6.—
In the longest drought Califor
nia has known, quail and duck are
dying of thirst, fish are dying in
drled-up rivers, deer ai’e invading
residential areas In search of food.
Migrating ducks have no water
on which to alight, and thousands
of them have died of thirst in the
San Joaqnlm grasslands.
Hatcheries have record num
bers of fish, but lack running
streams In which to put them.
Coastal rivers also are too shal
low to permit nrger fish reaching
their spawning mounds.http://trove.nla.gov.au/ndp/del/article/171267338?searchTerm=californian%20drought&searchLimits=

Once again the ‘better than nothing ‘ approach is seen in action , I wonder if the day will come when they decide how much ‘better ‘ these proxies actually are compared to nothing.
The real trouble comes when this ‘better than nothing ‘ is treated , has in this ‘research ‘, as unquestionable gold standard upon which great claims can be made. Now normally that is something you avoid in science becasue it hardly ever stands review and leads to poor pratice.
But then this is climate ‘science’ where reviews has little to do with the quality of your work and much to do with the ‘impact of its message ‘ , has for poor pratice , well time and again its has show there is no such concpet of poor pratice in climate science, ‘anything’ is acceptable and even honoured up to and including outright lying has long as it produces the ‘right results ‘

“We should be prepared for this type of snow drought to occur much more frequently because of rising temperatures,” Trouet said. “Anthropogenic warming is making the drought more severe.”
We had similar schtuff being said not that long ago her in Oz, endless drought, fams would never fill nyaa nyaa nyaa. And the it RAINED and RAINED and RAINED when the El Nino went ( we have the opposite to California, El Nino means dry and hot for us). Now the big environmental issues are the consequences of floods and of course who is to blame for houses being destroyed and the loss of life.
Same old same old. As that great American once said, there is a sucker born every day. Shamans, priests, climate scientist and other fear mondgers have been making a buck out of the fright bat scam for millenia. CAGW sells for the same reason murder thrillers and horror films sell. If you can sell the Dome, Independence Day or War of the Worlds to the viewing public, you can sell anything.

Gosh, trees are a thermometer, and trees are water level indicators. I bet they are also CO2 indicators. I bet separating these and many other effects is easy, since the claims are made with such certainty (sarc).

Idle question, and I really have no clue as to the answer, but can the water content between snowpacks be compared year to year?
The water content in snow depends on the temperature at which the snow fell. Anyone who has ever shoveled snow off a driveway knows this all too well. But in a given area where the snow does build up through the season, does it all compact to a point where the water content of 2 meters of snow in 1988 is the same as the water content of 2 meters of snow in 2008? If there can be a difference of a liter or two of water content over a square meter of area between years with identical snowpack height, that would be a significant difference in water over an area the size of the Sierras.
Of course significant differences in snowpack area and depth from year to year would make a huge difference in the amount of water locked up in the snow compared to the possibly paltry difference in water content of snowpack deposited at different temperatures, but when looking at tree rings year-to-year, any particular tree might have seen quite different amounts of snowpack, yet received the same amount of water.
So… I suppose a given snowpack depth and extent probably will have much the same water content compared to the same depth and extent in another year, but I’m not certain about that. I don’t have that knowledge.
The other factor I saw pointed out earlier in comments is the timing of the melt as it affects tree ring growth. A fast melt early that runs off like crazy will affect tree ring growth differently than a late slow melt that allows a lot of water to be absorbed by the ground around a tree. And runoff can also be affected by the location of the tree. How were the trees selected? Were the only suitable trees found to be in Yamal County, California? Was it a truly random sample of trees throughout the Sierras?

If you look at the annual cycle in reservoir storage, which includes precipitation and snowmelt, we haven’t touched 1976/1977. Zero annual cycle two years in a row with half the population of today.Ask Gerry, he was governor then too, he’s just smarter this time around.

So which are they? Are they thermometers or are they rain gauges? These Quercus douglasii are not growing in snow country at all. They grow at lower elevations and prefer dryer conditions. If they do react favorably to more rain, we have to ask, rain at what temperature. Some of the worst floods ever seen in California have come when cold early storms dumped feet of snow in the Sierra Nevada’s and then the ‘Pineapple Express’ rained it all off. It is very possible to end up with mega amounts of precipitation and no snow pack at 6,800′ elevation. According to the Quercus douglasii rain gauge thermometers every storm must produce snow pack? These folks wouldn’t understand the concept of a smell test if they were standing knee deep in bovine excrement.
And while were at it, how about if they might contact someone like Jim Steele to see if someone who actually lives in the area, who has studied water, habitat and the impact of droughts, might possibly have some insight that would add to their work before they publish utter nonsense. Maybe they could actually look at snowfall v. rainfall records to see what the actual correlation might be. Maybe they could look at cumulative rainfall totals from last year and see that we had less moisture last year than we have this year. But no. We already have oak trees from the valley to look at, so why bother with weather records. pffft!!!

This weekend I was on trip from San Francisco Bay area through 120 in Yosemite, Sierra to White Mountains. Last 4 years I was around this time on Tioga Pass, Ellery Lake too. I remember we played in snow there in August, September. There was a lot of snow under peaks. I fell to some hole up to my waist into snow once. This year there is simply no snow. Not a patch.
Yes this year was warmer in California no doubt.
But it is local. Permanent high pressure system in Pacific is causing west US coast to be warmer and east part colder.
Just compare snow cover for some years on:http://www.nohrsc.noaa.gov/nsa/index.html
And it is evident that there is more snow in 2015 in USA and Canada than in 2014, 2013, 2012, 2011, 2010.
Btw. it was raining around SF Bay Area yesterday. Very rare this time of year. All smoke in air is bringing precipitation.

“We should be prepared for this type of snow drought to occur much more frequently because of rising temperatures,” Trouet said. “Anthropogenic warming is making the drought more severe.”
I am going to put this beside Wadhams Arctic ice death spiral and the (Met Iffice ?) “children won’t know what snow is quotes.
I am betting on another poor snow this year followed by huge snow in 2017/2018 just looking at the ocean circulation off the west coast.
How’s that for a various levels prediction? In the other hand, according to Joe Bastardi, Taos, New Mexico should be a skiers paradise this winter. 😎😎😎😗

“Snowpack in the Sierras has been measured approximately since the 1930s, so the researchers checked their snowpack estimates from tree rings and the temperature reconstruction against actual snowpack measurements for 1930 to 1980.”
Funny that they use satellite images in the press release but ignore all the satellite data from 1980 to 2015.
Maybe it’s time for a new documentary: The Inconvenient Data.

In late January 1990, you could have said that the winter snowpack over Europe was the lowest in living memory, possibly longer.
It did not presage a new regime of snowless winters in Alpine ski resorts. Far from it.
Let’s see what the big el Nino brings California this winter – history would suggest some epic snowfalls and a huge snowpack.
We’ll find out in the next 6 months……

Sorry, but when scientists make so many unsupportable, biased statements to matters outside of the actual anomaly studied (e.g., the study gives no evidence of the cause of reduced snowfall, but they assign blame to AGW with no other science supporting that contention), then I have no faith in the validity of any of their data. Consciously or not, there is a high possibilty of their not recording the data correctly.
Measuring ring widths and counting the rings must be very tedious undertakings. I suspect if a data point did not meet their expectations, they re-examined it to the nth degree to find an error or a reason to adjust (ahem) it to a better value (and they may even keep a detailed explanation giving a very good reason for said adjustment). When a data point met their expectations, it was never looked at again.
I’ve seen this happen in the lab far too many times. It is the methodology of confirmation bias.

The Bay Area media quickly moved on from this one. Today they are harping about sea level rise. I’ve been personally observing the Bay shoreline for nearly 50 years. The profile is exceedingly shallow … there are mostly marshes and mudflats on these shores. Even a few inches of rise would be noticed. Thus far, after half a century … nothing. Of course, we do have a tectonic advantage over places like the US East Coast of coasts in many parts of Western Europe:
[IMG]http://geologycafe.com/california/pp1515/chapter8/fig8-4a.jpg[/IMG]

If a person is a “one in a million” then there are 7300 of them on earth. If there are 500 places on earth, then on average, one of them will be having a “once in 500 year” low snowpack. Or hot summer. Or heavy rains. Etc. Take enough places and enough variables and “once in 500 year” things happen every day.
This is why the global warming focus has turned from temperature (barely rising) to “extreme weather”. It is so easy to hype because of the convenience of numbers mentioned above.

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